The use of computers and computer networks pervade virtually every business and other enterprise in the modem world. With computers, users generate vast quantities of data that can be stored for a variety of purposes. This storehouse of data can grow at a phenomenal pace and become critically valuable to those who have generated it. Consequently, there is an ever-present need for data storage systems that improve on capacity, speed, reliability, etc.
In a single computer, the primary data storage device is usually a hard drive with a storage capacity measured in gigabytes. Additionally, computers may store data using such devices as CD-ROM drives, floppy disk drives, tape drive, etc. Within a computer network, the computers of the network may also store data on network servers or other data storage devices, such as those mentioned above, that are accessible through the network. For larger systems with even greater data storage needs, arrays of data storage disks may be added to the network.
Storage Area Networks (SANs) are an emerging technology being implemented to accommodate high-capacity data storage devices, particularly disk arrays, within a network. A SAN is essentially a high-speed network between client devices, such as servers and data storage devices, particularly disk arrays. A SAN overcomes the limitations and inflexibility of traditional attached data storage.
A SAN can overcome limitations of traditional attached data storage but also introduces new considerations. In particular, SANs experience competition for resources when more than one server is attempting to access the same data storage device. A typical storage device has a limited amount of bandwidth in its Input/Output (I/O) paths, and this bandwidth must be shared by the clients accessing the storage device.